How many BTU you need to heat your pool, or how much chiller to cool it
Put in the dimensions and the temperature you want, and out comes the output of the unit: in BTU/h for heating, using the US Department of Energy method, and in tons of refrigeration for cooling. With the World Aquatics and Resolución 929 temperature ranges in view.
Heating or cooling the pool
74,400 BTU/h
Heater output · 21.8 kW
| Water surface area | 32 m² |
| Water volume | 44.8 m³ |
| Water − air difference | 10 °C |
| Energy to go from 20 °C to 28 °C | 417 kWh |
| Heating time with that heater | 19.1 h |
Models that cover it
- Hayward HeatPro HP21124Theat pump91,800 BTU/h · 26.9 kWData sheet →
- Pentair UltraTemp 110heat pump89,200 BTU/h · 26.1 kWData sheet →
- Hayward HeatPro HP31204Theat pump that also cools98,100 BTU/h · 28.8 kWData sheet →
- Pentair UltraTemp 120 H/Cheat pump that also cools101,600 BTU/h · 29.8 kWData sheet →
- Hayward Universal H-Series H150gas · burns 150,000 BTU/h, at 82.7 % efficiency124,100 BTU/h · 36.4 kWData sheet →
- Pentair MasterTemp 175gas · burns 175,000 BTU/h, at 82 % efficiency143,500 BTU/h · 42.1 kWData sheet →
Heat pumps: what they deliver with the air in your case, between their two data sheet points. Gas: input times efficiency. Official data sheets read on 28 September 2026.
With the air at 18 °C, a heat pump delivers well below its data sheet figure, which is tested with air at 27 °C. This list already takes that off: that is why a larger model than its name suggests may come up.
Gas heaters are sized for installations up to about 600 m above sea level. Higher up they deliver less, and in high cities such as Bogotá or Tunja the manufacturer has to be asked for the altitude adjustment.
Size it with the pool covered at night: the biggest loss is evaporation, and a floating cover cuts it. A heater sized for an uncovered pool ends up oversized the day the cover goes on.
If the pool is indoors, the regulations also require the air in the room to be between 1 and 3 °C above the water.
Many pool heat pumps are reversible: they heat and cool with the same unit. If the climate calls for both over the year, it is worth pricing one of those before two separate units.
Where the calculation comes from
The heating output
US Department of Energy method for gas and heat pump pool heaters: BTU/h = pool surface area in square feet × (desired water temperature − average air temperature of the coldest month, in °F) × 12. It assumes a 3.5 mph wind at the water surface and a rise of 1 to 1¼ °F per hour; for 1½ °F multiply by 1.5, for 2 °F by 2. Here it is done in metres and degrees Celsius and converted.
The energy to change the temperature
Changing one cubic metre of water by one degree Celsius takes 1.163 kWh, which is the specific heat of water. It is the same going up as going down.
The temperatures
World Aquatics, Facilities Rules 2021–2025: swimming 25 to 28 °C (FR 2.1.13.1), water polo 25 to 27 °C (FR 4.1.4) and diving no less than 26 °C (FR 3.2.5). Resolución 929 de 2026 of the Colombian health ministry, technical annex, table 3: in indoor pools and similar structures, water at most 40 °C and air between 1 and 3 °C above the water. There is no standard for recreational use; the DOE works out its costs at 78, 80 and 82 °F, 26 to 28 °C.
The units
Official manufacturer documents, read on 28 September 2026: the Pentair UltraTemp installation guide and its archived data sheet (cooling output of the H/C models), the Pentair MasterTemp manual and data sheet (minimum 82 % efficiency), the Hayward HeatPro sell sheet LITHTPRO23 and the Hayward Universal H-Series brochure LITUHSBRO23. Heat pumps are tested to AHRI 1160. AstralPool is not included because its official data sheet could not be read.
The sun, for cooling
Colombia receives on average in the order of 4.5 kWh per square metre per day. Multiplied by the water surface area, it gives what the sun can put into the water at most.
What this tool does not claim
A tool that answers what its source does not say is worse than no tool at all. This is what is deliberately left unanswered here, and why.
- The DOE method is a sizing rule for outdoor pools, not a heat balance. A pool exposed to wind, on a hillside or in a dry climate needs more; a sheltered one, less.
- There is no equivalent official method for cooling. What you get is the energy to bring the temperature down and the ceiling of what the sun puts in; the real load is decided by a heat calculation for the specific case.
- The heating time does not subtract what keeps being lost while it rises. It is the minimum, not how long it will take.
- The output on a heat pump data sheet depends on the air temperature it was tested at, and it drops when the air cools. Between the two points the manufacturer publishes — 10 and 27 °C — a straight line is drawn: the real figure may be somewhat above or below.
- The models are a sample of two brands with readable official data sheets, not the whole market. It is not a buying recommendation: the practice has no commercial relationship with any brand, and prices are not included.
- The recreational ranges are not a standard: they are the closest public reference there is.
I have a plot and I want to build on it.
We check what the planning rules allow on your plot, what can be built and what it costs, before drawing anything. Then we develop the full project through to the drawings the building permit is filed with.